Optical Study of Chitosan-Ofloxacin Complex for Biomedical Applications

Chitosan ofloxacin complex was prepared in isopropyl alcohol under mild conditions. The ionic complexation between chitosan and ofloxacin was confirmed by Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopy. The crystallinity, thermal, surface morphology and optical properties were evaluated by X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis) spectroscopy, photoluminescence (PL) spectroscopy and second harmonic generation (SHG) studies, respectively. Absorption of the complex was high (10⁶cm^?1) with an optical band gap of 3.80 eV. The chitosan-ofloxacin complex may be considered as a novel optical material from biomedical application point of views. It may find applications as biosensors and environmentally sensitive membranes and artificial membranes.     

Activated Fly Ash Catalyzing the Synthesis of Novel Potent 4-Thiazolidinones of 4-Amino Antipyrine Anils Using CEM Discover Microwave Methodology and Their Virtual Screening

Abstract

Fly ash, an industrial waste, has been used as an efficient and cost-effective activating catalyst for the synthesis of new potent thiazolidinones (4a–n), starting from imine (3a–n) and thioacetic acid. The reactions were performed under CEM Discover microwave irradiation in solvent-free conditions. This reaction is scalable to a multigram scale and the methodology has resulted in an efficient synthesis. Herein, a benign, environment friendly, efficient, and extremely fast procedure for the synthesis of thiazolidinones have been demonstrated. The produced thiazolidinone molecules were characterized on the basis of elemental analysis, infrared (IR), mass spectral, and ¹H NMR spectral data. The synthesized moieties were screened virtually and discussed for their possible biological activity.     

Use of Adsorbents for Recovery of Acetic Acid from Aqueous Solutions Part III—Solvent Regeneration

Solvent leaching was investigated as a method of regeneration for activated carbons and polymer sorbents loaded with acetic acid by contact with aqueous solutions. Both batch-equilibration and fixed-bed experiments were employed. Methanol, methyl acetate, and acetone are suitable regeneration solvents for most activated carbons. Amoco GX-031 is an exception, giving incomplete regeneration. Methanol provides still more efficient regeneration for macroreticular styrene-divinylbenzenes adsorbents. Among basic sorbents, amine resins give incomplete regeneration by solvent leaching, as does a poly N oxide. Polybenzimidazole, a weaker base, gives higher recoveries of acetic acid when leached by solvents. Poly(4-vinylpyridine) is regenerated completely and efficiently by methanol, methyl acetate, and acetone in a fixed-bed geometry. It thus appears that an intermediate degree of basicity is desirable in a synthetic sorbent for acetic acid – strong enough to give the uptake benefits of acid-base interactions, but weak enough to be regenerable.     

Enhanced field emission characteristics of boron doped diamond films grown by microwave plasma assisted chemical vapor deposition

Boron doped diamond films were synthesized on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) technique. The effect of B₂O₃ concentration varied from 1000 to 5000 ppm on the field emission characteristics was examined. The surface morphology and quality of films were characterized by scanning electron microscope (SEM) and Raman spectroscopy. The surface morphology obtained by SEM showed variation from facetted microcrystal covered with nanometric grains to cauliflower of nanocrystalline diamond (NCD) particles with increasing B₂O₃ concentration. The Raman spectra confirm the formation of NCD films. The field emission properties of NCD films were observed to improve upon increasing boron concentration. The values of the onset field and threshold field are observed to be as low as 0.36 and 0.08 V/μm, respectively. The field emission current stability investigated at the preset value of ∼1 μA is observed to be good, in each case. The enhanced field emission properties are attributed to the better electrical conductivity coupled with the nanometric features of the diamond films.     

Improvement in micro-structural and mechanical properties of zinc film by surface treatment with low temperature argon plasma

Nanocrystalline zinc films were deposited on gold coated borosilicate glass substrates by thermal evaporation method using zinc powders as the source material and then treated with argon plasma at various temperatures. From X-ray diffraction study, the as-deposited films are found to be metallic Zn and polycrystalline in nature. The crystalline nature improves with the increase of temperature up to 200 °C and decreases with the further increase of temperature to 300 °C. The binding energy observed for Zn 2p_3/2, and the binding energy separation between Zn 2p_3/2 and Zn 2p_1/2 in the X-ray photoelectron spectrum indicate that the films are metallic zinc films. Transmission electron microscopic study shows hexagonal shaped grains having size ∼58 nm upon treatment with Ar plasma. It is clearly shown the grain growth and distinct grain boundary with the increase in temperature. The average Young's modulus (E) and hardness (H) are measured to be 84 GPa and 4.0 GPa for as-deposited film, whereas 98 GPa and 5.8 GPa for plasma treated film at 200 °C. The enhancement in mechanical properties is attributed to improvement in crystalline nature of the film and better interlinking between grains and boundaries.     

Ionic Liquid–Mediated Synthesis of Coumarin-3-carboxylic Acids via Knoevenagel Condensation of Meldrum's Acid with ortho-Hydroxyaryl Aldehydes

A simple, efficient, and green protocol for synthesis of coumarin-3-carboxylic acids is described via Knoevenagel condensation of Meldrum's acid with ortho-hydroxyaryl aldehydes in [Hmim]Tfa ionic liquid, which was found to give better results than other ionic liquids. Furthermore, ionic liquid is easily reused without any appreciable loss in activity.     

Generators for the derivation modules and the relation ideals of certain curves

LetO be a curve in the affine algebroide-space over a fieldK of characteristic zero. LetD be the module ofK-derivations andP the relation ideal ofO. Generators forD andP are computed in several cases. It is shown in particular that in the case of a monomial curve defined by a sequence ofe positive integers somee−1 of which form an arithmetic sequence, μO ≤ 2e - 3 and μ(P)≤e(e−1)/2.     

Synthesis and characterisation of cobalt(III) complexes with 1,1-dimethylethylenediamine (1,1-dmen) and 1,2-propanediamine (pn)

Two stable diamine complexes [Co(1,1-dmen)₂(NCS)₂]SCN · (H₂O)_1.5 (1) and [Co(pn)₂(NCS)₂]SCN · (H₂O)_1.5 (2) have been synthesised and characterised by elemental analysis, i.r. and electronic spectra and t.g.a. The structure of (1) has been confirmed by single-crystal X-ray diffraction and reveals that the cobalt complex has octahedral geometry and consists of two crystallographically independent cations, both situated on centres of inversion. In the crystal structure of (1), free H₂O molecules and SCN^– ions form an extensive hydrogen bonding network with the cation. It is an ordered pseudo-polymorph of a previous structure determination. Both (1) and (2) are diamagnetic.     

Three new sesterterpenoid antibiotics from the marine sponge Luffariella variabilis (polejaff)

Structures of three new sesterterpenoid antibiotics 2, 3, and 4, isolated from a marine sponge have been determined by spectral analysis and chemical transformations.